(1) FIELD OF THE INVENTION
The invention relates to a pressure switch for sensing a control fluid pressure in response to variations of a monitored fluid pressure either above or below a desired normal value.
(2) BRIEF DESCRIPTION OF THE PRIOR ART
Pressure switches for sensing a control fluid pressure and for shifting a valve element in response thereto have been widely employed in the prior art. In many instances, the prior art has involved incorporation of a "spool" assembly which is manipulatable between positions in response to a pre-determined fluid pressure either of a liquid or a gas for shifting across a port or a passage to detect a pre-determined level in the sourced fluid pressure, or, alternatively, to actuate another mechanism.
In some instances, it may be desirable to sense a pre-determined level of a source of fluid pressure, and either provide an electronic indication of such sensed level or, alternatively, to activate an electronic signal for actuating an auxiliary mechanism by electric means, including a micro-switch or a fiber-optic-actuated mechanism which is, in turn, actuated by such micro-switch.
In many instances, it would be desirable to provide a single pressure switch assembly which may be responsive to a number of pre-selected levels of fluid pressure in the source or fluid conduit. In the past, any such pressure switch assembly would have to be enlarged, considerably, to incorporate a complex valving system which could be manipulated to provide one of several fluid levels for actuation. Such construction is cumbersome and expensive.
The present invention addresses the problems set forth above and provides a remedy therefore.